397
warranted when it comes specifically to the jurisdiction to decide incidentally external issues. In this latter case, as we shall see, it cannot be ruled out that, even though
incidental determinations should be included in the reasoning part of a judgment, a
binding (“stabilizing”) effect might nonetheless be attached to them. Thus, given
the fact that in this case tribunals could not only reach beyond the parties’ submissions, but could make determinations on matters that may even lie beyond their
jurisdiction ratione materiae, a more prudent approach would require that the
“necessity” requirement referred to in Chagos be treated as the normal criterion to
be applied in order to determine the scope of incidental jurisdiction. True, it is hard
to deny that the identification of the proper criterion depends, at least in part, on the
specific circumstances of each case. A number of factors may affect the determination of the proper criterion. For example, importance should probably be attached to
the attitude of the parties before the Tribunal. When the applicant brings, together
with an UNCLOS dispute, a non-UNCLOS issue before a tribunal, it may well happen that the respondent does not contest the (incidental) jurisdiction over the second
issue. One may speculate whether in cases like this a tribunal could take a more
flexible approach in addressing the scope of its incidental jurisdiction. Should the
attitude of the parties not reveal a willingness to discuss non-UNCLOS matters,
however, a strict and cautious approach in assessing the conditions for incidental
jurisdiction seems to be required. Be that as it may, only future case law will tell
how UNCLOS tribunals will manage this kind of situations.
Secondly, even if UNCLOS tribunals should regard the “necessity” requirement
referred to in Chagos as the normal criterion to be applied in order to determine the
scope of their incidental jurisdiction, there still remains to be seen how the necessity
test will be carried out in practice. “Necessity” might turn out as a critical aspect of
the Chagos test. Indeed, at a closer look, it can be intended either as a factor justifying the incidental jurisdiction and as an element upon which the characterization of
the dispute is principally based. In this latter case, it might well be stated that if one
external issue, however presented as “incidental”, must be preliminarily decided in
order to reach a decision on the “principal” issue, this means that the external issue
constitutes in fact the very subject matter of the dispute. On this assumption, by
drawing a parallelism with the doctrine of indispensable parties,
69
Tzeng suggests
that “an international court or tribunal cannot exercise jurisdiction over a dispute if
a legal issue outside of its jurisdiction ratione materiae forms the ‘very subjectmatter’ of the decision, which is the case if and only if the decision requires a ‘prerequisite determination’ on that legal issue”.
70
Seen in this light, rather than
triggering the incidental jurisdiction of the tribunal, the requirement of “necessity”
would have the opposite effect. It would simply provide evidence that the very
subject- matter of the dispute does not fall within the jurisdiction, so that the exercise
69 ICJ, Case Concerning East-Timor (Portugal v. Australia), Judgment, 30 June 1995, para. 28;
ICJ, Case of the Monetary Gold Removed from Rome in 1943 (Italy v. France, United Kingdom
and United States), Judgment, 15 June 1954, p. 32. For a similar comparison, see also Buga (2012),
p. 80.
70 Tzeng (2017), p. 128.
Between Consent and Effectiveness: Incidental Determinations and the Expansion…
warranted when it comes specifically to the jurisdiction to decide incidentally external issues. In this latter case, as we shall see, it cannot be ruled out that, even though
incidental determinations should be included in the reasoning part of a judgment, a
binding (“stabilizing”) effect might nonetheless be attached to them. Thus, given
the fact that in this case tribunals could not only reach beyond the parties’ submissions, but could make determinations on matters that may even lie beyond their
jurisdiction ratione materiae, a more prudent approach would require that the
“necessity” requirement referred to in Chagos be treated as the normal criterion to
be applied in order to determine the scope of incidental jurisdiction. True, it is hard
to deny that the identification of the proper criterion depends, at least in part, on the
specific circumstances of each case. A number of factors may affect the determination of the proper criterion. For example, importance should probably be attached to
the attitude of the parties before the Tribunal. When the applicant brings, together
with an UNCLOS dispute, a non-UNCLOS issue before a tribunal, it may well happen that the respondent does not contest the (incidental) jurisdiction over the second
issue. One may speculate whether in cases like this a tribunal could take a more
flexible approach in addressing the scope of its incidental jurisdiction. Should the
attitude of the parties not reveal a willingness to discuss non-UNCLOS matters,
however, a strict and cautious approach in assessing the conditions for incidental
jurisdiction seems to be required. Be that as it may, only future case law will tell
how UNCLOS tribunals will manage this kind of situations.
Secondly, even if UNCLOS tribunals should regard the “necessity” requirement
referred to in Chagos as the normal criterion to be applied in order to determine the
scope of their incidental jurisdiction, there still remains to be seen how the necessity
test will be carried out in practice. “Necessity” might turn out as a critical aspect of
the Chagos test. Indeed, at a closer look, it can be intended either as a factor justifying the incidental jurisdiction and as an element upon which the characterization of
the dispute is principally based. In this latter case, it might well be stated that if one
external issue, however presented as “incidental”, must be preliminarily decided in
order to reach a decision on the “principal” issue, this means that the external issue
constitutes in fact the very subject matter of the dispute. On this assumption, by
drawing a parallelism with the doctrine of indispensable parties,
69
Tzeng suggests
that “an international court or tribunal cannot exercise jurisdiction over a dispute if
a legal issue outside of its jurisdiction ratione materiae forms the ‘very subjectmatter’ of the decision, which is the case if and only if the decision requires a ‘prerequisite determination’ on that legal issue”.
70
Seen in this light, rather than
triggering the incidental jurisdiction of the tribunal, the requirement of “necessity”
would have the opposite effect. It would simply provide evidence that the very
subject- matter of the dispute does not fall within the jurisdiction, so that the exercise
69 ICJ, Case Concerning East-Timor (Portugal v. Australia), Judgment, 30 June 1995, para. 28;
ICJ, Case of the Monetary Gold Removed from Rome in 1943 (Italy v. France, United Kingdom
and United States), Judgment, 15 June 1954, p. 32. For a similar comparison, see also Buga (2012),
p. 80.
70 Tzeng (2017), p. 128.
Between Consent and Effectiveness: Incidental Determinations and the Expansion…